Camera, interchangeable lens apparatus, adapter apparatus, control method, and storage medium

ABSTRACT

A camera includes a lens-camera communication controller and an adapter-camera communication controller. The camera-lens communication channel includes a first data communication channel used during a data communication and a first notification channel used for a notification of a timing of a communication via the first data communication channel. The camera-adapter communication channel includes a second data communication channel used during the data communication and a second notification channel used for a notification of a timing of a communication via the second data communication channel.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a Continuation of International Patent ApplicationNo. PCT/JP2018/020714, filed on May 30, 2018, which claims the benefitof Japanese Patent Applications Nos. 2017-107260, filed on May 31, 2017,and 2018-102897, filed on May 30, 2018, each of which is herebyincorporated by reference herein in their entirety.

BACKGROUND OF THE INVENTION Field of the Invention

The present invention relates to a camera system including a camera, aninterchangeable lens apparatus (simply referred to as interchangeablelens hereinafter), and an adapter apparatus (simply referred to as anadapter hereinafter) located between the camera and the interchangeablelens, which can communicate with each other.

Description of the Related Art

In an interchangeable lens type camera system including a camera towhich an interchangeable lens is detachably attachable, a communicationis performed for the camera to control the operation of theinterchangeable lens and for the interchangeable lens to provide thecamera with data necessary for its control and imaging. In particular,in imaging a recording use motion image and a live-view display usemotion image with the interchangeable lens, a smooth lens control isrequired at an imaging cycle, so it is necessary to synchronize theimaging timing of the camera and the control timing of theinterchangeable lens with each other. Thus, the camera needs to completea data reception from the interchangeable lens and a transmission of acommand, such as a variety of instructions and requests, to theinterchangeable lens within the imaging cycle. However, as a data amountreceived by the camera from the interchangeable lens becomes larger orthe imaging cycle becomes shorter (or the frame rate becomes higher), acommunication of a large amount of data at higher speed is required.

An adapter such as a wide converter or a teleconverter (extender) may bemounted between the camera and the interchangeable lens. In this case, acommand transmission from the camera to the interchangeable lens and adata transmission from the interchangeable lens to the camera areperformed via the adapter. Furthermore, for proper AF, AE, etc. in thecamera, not only data on the interchangeable lens but also data specificto the adapter is required. A camera system disclosed in Japanese PatentLaid-Open No. 2012-037692 performs the command transmission from thecamera to the adapter and the data transmission from the adapter to thecamera by a common communication channel as that for the commandtransmission from the camera to the interchangeable lens and the datatransmission from the interchangeable lens to the camera. In otherwords, a one-to-many communication is achieved among the camera, theinterchangeable lens, and the adapter using one communication channel.

However, in the one-to-many communication using only a singlecommunication channel, for example, the camera cannot transmit a commandto the interchangeable lens or receive data from the interchangeablelens while data is transmitted from the adapter to the camera. As aresult, an expedited communication between the camera and theinterchangeable lens is hindered.

SUMMARY OF THE INVENTION

The present invention provides a camera, an interchangeable lensapparatus, and an adapter apparatus, each of which can expedite acommunication between the camera and the interchangeable lens apparatusand smooth a communication between the camera and the adapter apparatus.

A camera according to one aspect of the present invention to which aninterchangeable lens apparatus is connected via at least one adapterapparatus includes a lens-camera communication controller configured tocommunicate with the interchangeable lens apparatus via a camera-lenscommunication channel connected from the camera to the interchangeablelens apparatus via the adapter apparatus, and an adapter-cameracommunication controller configured to communicate with the adapterapparatus via a camera-adapter communication channel provided separatelyfrom the camera-lens communication channel with the adapter apparatus.The camera-lens communication channel includes a first datacommunication channel used during a data communication and a firstnotification channel used for a notification of a timing of acommunication via the first data communication channel, and thecamera-adapter communication channel includes a second datacommunication channel used during the data communication and a secondnotification channel used for a notification of a timing of acommunication via the second data communication channel.

A camera system including the above camera, an interchangeable lensconnected to the camera, and an adapter apparatus connected to thecamera and the adapter apparatus also constitute another aspect of thepresent invention.

An adapter apparatus according to another aspect of the presentinvention to which the camera and interchangeable lens are connectedincludes a relay channel for forming part of a camera-lens communicationchannel used for a communication between the camera and theinterchangeable lens, and an adapter-camera communication controllerconfigured to communicate with the camera via a camera-adaptercommunication channel provided separately from the relay channel withthe camera. The camera-lens communication channel includes a first datacommunication channel used during a data communication and a firstnotification channel used for a notification of a timing of acommunication via the first data communication channel, and thecamera-adapter communication channel includes a second datacommunication channel used during a data communication and a secondnotification channel used for a notification of a timing of acommunication via the second data communication channel.

An interchangeable lens apparatus according to another aspect of thepresent invention connected to an adapter apparatus and a camera via theadapter apparatus includes a first lens-camera communication controllerconfigured to communicate with the camera via a camera-lenscommunication channel connected to the interchangeable lens from thecamera via the adapter apparatus, and a second lens-camera communicationcontroller provided separately from the camera-lens communicationchannel and configured to communicate with the camera via acommunication channel including a camera adapter communication channelconnected to the camera and the adapter. The first camera-lenscommunication channel includes a first data communication channel usedduring a data communication and a first notification channel used for anotification of a timing of communication via the first datacommunication channel, and the communication channel includes thecamera-adapter communication channel include a second data communicationchannel used during a data communication and a second notificationchannel used for a notification of a timing of a communication via thesecond data communication channel.

A control method for a camera connected to an interchangeable lensapparatus via at least one adapter apparatus includes the steps ofcommunicating with the interchangeable lens apparatus via a camera-lenscommunication channel connected from the camera to the interchangeablelens apparatus via the adapter apparatus, and communicating with theadapter apparatus via a camera-adapter communication channel from acamera-lens communication channel with the adapter apparatus separate,and controlling an operation of the interchangeable lens using dataobtained through a communication with the interchangeable lensapparatus, and controlling an operation of the adapter apparatus usingdata obtained through a communication with the adapter apparatus. Thecamera-lens communication channel includes a first data communicationchannel used during a data communication and a first notificationchannel used for a notification of a timing of a communication via thefirst data communication channel, and the camera-adapter communicationchannel includes a second data communication channel used during a datacommunication and a second notification channel used for a notificationof a timing of communication via the second data communication channel.

The imaging control program as a computer program that executes theabove control method also constitutes another aspect of the presentinvention.

Further features of the present invention will become apparent from thefollowing description of exemplary embodiments with reference to theattached drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a block diagram showing a configuration of a camera systemaccording to a first embodiment of the present invention.

FIG. 2 is a flowchart showing lens control processing according to thefirst embodiment.

FIGS. 3A and 3B explain a first communication according to the firstembodiment.

FIG. 4 is a flowchart illustrating adapter information acquisitionprocessing according to the first embodiment.

FIGS. 5A and 5B explain a data occupancy status of each communicationaccording to the first embodiment.

FIG. 6 is a block diagram showing a configuration of a camera systemaccording to a second embodiment of the present invention.

FIG. 7 is a flowchart showing lens control processing according to thesecond embodiment.

FIG. 8 is a diagram for explaining a first communication when aninterchangeable lens is activated from a camera according to the secondembodiment.

FIG. 9 is a diagram for explaining the first communication when aninterchangeable lens is activated from the interchangeable lensaccording to the second embodiment.

FIG. 10 is a flowchart illustrating adapter control processing accordingto the second embodiment.

FIGS. 11A and 11B explain a second communication according to the firstembodiment.

FIG. 12 is a diagram for explaining a third communication (one-to-many)according to the first embodiment.

FIG. 13 is a diagram for explaining the third communication (one-to-one)according to the first embodiment.

DESCRIPTION OF THE EMBODIMENTS

Referring now to the accompanying drawings, a description will be givenof embodiments according to the present invention.

First Embodiment

FIG. 1 illustrates a configuration of a camera system according to afirst embodiment of the present invention. The camera system includes acamera 20, an interchangeable lens apparatus (referred to as aninterchangeable lens hereinafter) 10, and two adapter apparatuses(referred to as adapters hereinafter) 30 and 40 disposed between thecamera 20 and the interchangeable lens 10. The camera system has a firstcommunication use camera-lens communication channel 100 (referred to asa first communication channel 100 hereinafter) for transmitting acommand for an instruction and a request from the camera 20 to theinterchangeable lens 10. In addition, the camera system includes,separate from the communication channel 100, a second communication uselens-camera communication channel (referred to as a second communicationchannel 200 hereinafter) for transmitting data indicating optical data,status, and the like from the interchangeable lens 10 to the camera 20.The camera system further includes a third communication usecamera-adapter communication channel (referred to as a thirdcommunication channel 300 hereinafter) for communicating data indicatinga command, optical data of each adapter, and the state and the likebetween the camera 20 and the two adapters 30 and 40.

The interchangeable lens 10 has an imaging optical system including aplurality of movable optical elements such as a lens and an aperturestop or diaphragm (iris). The camera 20 includes an image sensor 204that captures an object image formed by the imaging optical system, andgenerates an image signal using an output signal from the image sensor204. The adapter 40 is detachably connected (attached) to the mount 201of the camera 20 at a mount 402. The adapter 30 is detachably connectedto a mount 401 of the adapter 40 at its mount 302. The adapter 30includes an extender, a wide converter, or the like, and the adapter 40includes an ND adapter or the like, and includes adapter opticalelements 309 and 409 such as a magnification varying lens and an NDfilter, respectively. Further, the interchangeable lens 10 is detachablyconnected to the mount 301 of the adapter 30 at its mount 101.

When the mounts 101, 301, 302, 401, 402, and 201 are all connected,first communication contacts 102, 303, 306, 403, 406, and 202 providedto the respective mounts are electrically connected to each other, and acamera-lens communication channel is formed for the first communication.The first communication is used for a communication used for the camera20 to control the operation of the movable optical element of theinterchangeable lens 10.

When the mounts 101, 301, 302, 401, 402, and 201 are all connected,second communication contacts 103, 304, 307, 404, 407, and 202 providedto the respective mounts are electrically connected to each other, and acamera-lens communication channel is formed for the secondcommunication. The second communication is used to transmit optical dataof the interchangeable lens 10 (referred to as lens optical datahereinafter) and data indicating the state of the interchangeable lens10 (referred to as lens state data hereinafter) to the camera 20.Further, by connecting the mounts 101, 301, 302, 401, 402, and 201,third communication contacts 104, 305, 308, 405, 408, and 203 providedto the respective mounts are electrically connected to each other toform a camera-adapter communication channel for the third communication.The third communication is a one-to-many communication between thecamera 20 and the two adapters 30 and 40. The third communication isused for the camera 20 to transmit a command for controlling theiroperations to the adapters 30 and 40. Further, it is used for theadapters 30 and 40 to transmit optical data to the camera 20 of adapteroptical elements 309 and 409 and operation data indicating a useroperation to the adapters 30 and 40. The following description willrefer to the respective optical data of the adapters 30 and 40 as firstadapter optical data and second adapter optical data. The respectiveoperation data of the adapters 30 and 40 will be referred to as firstadapter operation data and second adapter operation data. The thirdcommunication is also used for a communication between theinterchangeable lens 10 and the adapters 30 and 40.

In the interchangeable lens 10, the movable optical elements in theimaging optical system described above include a focus lens 105, amagnification varying lens 106, an iris 107, and an image stabilizationlens 108. The focus lens 105 moves in the optical axis direction of theimaging optical system to perform focusing. The magnification varyinglens 106 moves in the optical axis direction to perform a magnificationvariation. The iris 107 performs a light amount adjustment. The imagestabilization lens 108 moves (shifts) in a direction orthogonal to theoptical axis direction to reduce an object image blur caused by a camerashake due to camera shake or the like.

A focus controller 109 includes a focus actuator that moves the focuslens 105, a focus driver that controls driving of the focus lens 105,and a focus position sensor that detects the position of the focus lens105. A zoom controller 110 includes a zoom adapter that moves themagnification varying lens 106, a zoom driver that controls its driving,and a zoom position sensor that detects the position of themagnification varying lens 106. An iris controller 111 includes an irisdriver that drives an iris motor provided to the iris 107 and an irisposition sensor that detects an open/close position (F-number oraperture value) of the iris 107. An image stabilization controller 112includes an image stabilization actuator that shifts the imagestabilization lens 108, an image stabilization driver that controls itsdriving, and a shift position sensor that detects the shift position ofthe image stabilization lens 108.

A shake detection unit 113 includes a vibration gyro and the like, anddetects a camera shake amount that is a shake amount of theinterchangeable lens 10 (or a camera system).

A lens controller 114 controls the operations of the focus lens 105, themagnification varying lens 106, and the iris 107 through the focus,zoom, and iris controllers 109 to 111 in accordance with the lenscontrol command received from a camera controller 205 in the camera 20.The lens controller 114 controls the operation (shift) of the imagestabilization lens 108 through the image stabilization controller 112 inresponse to receiving the lens control command. The lens controller 114transmits lens optical data and lens state data to the camera controller205. The lens controller 114 communicates with the camera controller 205through a first lens communicator 115 and a second lens communicator116, and communicates with the adapters 30 and 40 through a third lenscommunicator 117.

The first lens communicator 115 constitutes a camera-lens communicationcontroller together with the lens controller 114, and performs a firstcommunication with the camera controller 205. The first communication isused to receive a command, such as a lens control command, from thecamera controller 205.

The second lens communicator 116 performs a second communication withthe camera controller 205. The second communication is used to transmitlens optical data and lens state data to the camera controller 205. Thethird lens communicator 117 constitutes an adapter-lens communicationcontroller together with the lens controller 114, and performs a thirdcommunication with third adapter communicators 310 and 410 in theadapters 30 and 40. The third communication between the third adaptercommunicators 310 and 410 is also used to transmit lens optical data andlens state data from the lens controller 114 to the adapter controllers311 and 411.

The lens controller 114 and the lens first to third communicators 115 to117 include a computer such as a CPU provided in the interchangeablelens 10. A lens operation member 118 is an operation member operated bythe user in the interchangeable lens 10, and includes a switch, anelectronic ring, or the like.

In the camera 20, the image sensor 204 includes a CMOS image sensor orthe like, and photoelectrically converts (captures) an object image. Thecamera controller 205 converts the output signal from the image sensor204 into an image signal and outputs it to an image display unit 206.

In addition, the camera controller 205 transmits a lens control commandto the lens controller 114 to control the operation of theinterchangeable lens 10 and receives lens optical data and lens statedata from the lens controller 114. The camera controller 205communicates with the lens controller 114 through the first cameracommunicator 207 and the camera second communicator 208, andcommunicates with the adapters 30 and 40 through the third cameracommunicator 209.

The first camera communicator 207 constitutes a lens-cameracommunication controller together with the camera controller 205, andperforms a first communication with the first lens communicator 115. Asdescribed above, the first communication is used to transmit a commandsuch as a lens control command from the camera controller 205 to thelens controller 114, or to transmit data from the lens controller 114 tothe camera controller 205. The camera second communicator 208 performs asecond communication with the first lens communicator 115. As describedabove, the second communication is used to receive lens optical data andlens state data from the lens controller 114.

The third camera communicator 209 constitutes an adapter-cameracommunication controller together with the camera controller 205, andperforms a third communication with the third adapter communicators 310and 410. The third communication is used to transmit an adapter controlcommand and an adapter transmission requesting command (a command forrequesting a transmission of adapter specific information) to theadapter controllers 311 and 411. Moreover, the third communication isused to receive the adapter specific information from the adaptercontrollers 311 and 411. The adapter specific information includes, forexample, first and second adapter optical data and first and secondadapter operation data. The camera controller 205 and the camera firstto third communicators 207 to 209 include a computer such as a CPUprovided in the camera 20. In the first and third communications, atleast one of a communication method, a communication timing, acommunication speed (communication rate), and a communication voltage isdifferent from each other.

The image display unit 206 includes a liquid crystal monitor or thelike, and displays an image signal (captured image) from the cameracontroller 205. The camera operation member 210 is an operation memberoperated by the user in the camera 20 in order to set an imagingcondition, and includes a dial, a switch, or the like.

In the adapters 30 and 40, the adapter optical elements 309 and 409described above are optical elements for adding a specific opticalaction to the interchangeable lens 10, and include a magnificationvarying lens, an ND filter, or the like. In this embodiment, the adapter30 is an extender having a magnification varying lens as the adapteroptical element 309, and the adapter 40 is an ND adapter having an NDfilter as the adapter optical element 409. The adapter optical elementmay be an member other than a magnification varying lens or an NDfilter.

The adapter controllers 311 and 411 control the operations of theadapters 30 and 40 (insertion into and ejection from the imaging opticalpath of the magnification varying lens and the ND filter) according tothe adapter control command received from the camera controller 205.

The adapter controllers 311 and 411 communicate with the cameracontroller 205 and the lens controller 114 via the third adaptercommunicators 310 and 410. The third adapter communicators 310 and 410together with the adapter controllers 311 and 411 constitute acamera-adapter communication controller and a lens-adapter communicationcontroller, and perform the third communication with the third cameracommunicator 209 and the third lens communicator 117. As describedabove, the third communication with the third camera communicator 209 isa communication used to receive the adapter control command and theadapter request command from the camera controller 205, and to transmitthe first and second adapter optical data to the camera controller 205.As described above, the third communication with the third lenscommunicator 117 is used to receive lens optical data and lens statedata from the lens controller 114.

The adapter controller 311 and the third adapter communicator 310include a CPU provided in the adapter 30. The adapter controller 411 andthe third adapter communicator 410 include a computer such as a CPUprovided in the adapter 40.

The adapter operation members 312 and 412 are operation members operatedby the user in the adapters 30 and 40, and include switches, electronicrings, and the like. Here, a predetermined function is assigned to theoperation of the adapter operation members 312 and 412. Alternatively, auser's favorite function is assigned through an unillustrated settingunit of the camera 20. Illustrative functions for the operation of theadapter operation members 312 and 412 include, for example, thefollowing. When the adapter operation members 312 and 412 are switches,they are at least one of ON/OFF of the image stabilization function,setting of the image stabilization level of the image stabilizationfunction, and switching between the autofocus and the manual focus. Whenthe adapter operation members 312 and 412 are electronic rings, theadapter operation members 312 and 412 are at least one of an adjustmentfunction of an aperture position (aperture diameter), an adjustmentfunction of a focus position, and an adjustment function of a zoomposition of the interchangeable lens 10. At least one of the apertureposition, the focus position, and the zoom position is adjusted in thelens 10 by an adjustment amount corresponding to the amount by which theelectronic ring is operated.

Referring now to a flowchart in FIG. 2, a description will be given ofprocessing in which the camera 20 (camera controller 205) controls theinterchangeable lens 10 (lens controller 114). Each of the cameracontroller 205 and the lens controller 114 executes this processing (andeach processing described later) in accordance with an imaging controlprogram that is a computer program.

When the camera 20 is activated in S201, the camera controller 205proceeds to S202. In the step S202, the camera controller 205 suppliesthe power to the interchangeable lens 10 and the adapters 30 and 40 viaan unillustrated power supply mount contact.

In the step S203, the camera controller 205 causes the first cameracommunicator 207 to detect the communication voltage used by theinterchangeable lens 10, and sets the communication voltage used by thefirst camera communicator 207 and the camera second communicator 208according to the detection result. Thereafter, the first cameracommunicator 207 and the second camera communicator 208 performs thefirst communication and the second communication with the first lenscommunicator 115 and the second lens communicator 116, respectively,using the set communication voltage. The processing in which the firstcamera communicator 207 detects the communication voltage of theinterchangeable lens 10 will be described later.

Next, in S204, the lens controller 114 transmits, through the first lenscommunicator 115 (and the first camera communicator 207), ID informationof the interchangeable lens 10 such as a lens name and lensspecifications (referred to as a lens ID hereinafter) to the cameracontroller 205. The camera controller 205 receives the lens ID via thefirst camera communicator 207. The lens controller 114 transmits lensstate data indicating the current state (lens state) of theinterchangeable lens 10 to the camera controller 205 via the second lenscommunicator 116 (and the camera second communicator 208). The cameracontroller 205 receives the lens state data via the camera secondcommunicator 208.

The lens state data includes the current positions (referred to as anoptical element position hereinafter) of the focus lens 105, themagnification varying lens 106, the iris 107, and the imagestabilization lens 108 acquired from the focus, zoom and iriscontrollers 109, 110, and 111 and the image stabilization controller 112(referred to as the lens image data hereinafter). The lens state dataincludes a value obtained by normalizing the camera shake amountacquired from the shake detection unit 113, and lens operation dataindicating the operation amount and operation state of the useroperation acquired from the lens operation member 118. When the lensoperation member 118 is an electronic ring, the operation amount perunit time of the electronic ring may be included in the lens operationdata. If the lens operation member 118 is a switch, the ON/OFF state ofthe switch may be included in the lens operation data.

Next, in S205, the camera controller 205 determines lens state datareceived from the lens controller 114 by the second communication basedon the lens state data acquired in S204. Then, a command requesting atransmission of the determined lens state data is transmitted to thelens controller 114 via the first camera communicator 207 (and the firstlens communicator 115).

In the step S206, the lens controller 114 determines the lens statusdata indicating the current lens state to be transmitted to the cameracontroller 205 based on the command received from the camera controller205 via the first lens communicator 115 in the step S205.

Next, in S207, the lens controller 114 transmits the determined lensstate data to the camera controller 205 via the second lens communicator116 (and the camera second communicator 208).

In the step S208, the camera controller 205 determines an imagingcondition based on the lens state data received from the lens controller114 via the camera second communicator 208, the magnification varyingratio of the adapter (extender) 30, and the transmittance of the adapter(ND adapter) 40. Then, imaging is performed under the imagingconditions. The imaging condition includes an object distance, a focallength, an F-number, a T value, a camera shake amount per unit time, anda shake correction angle for an image stabilization (shift amount of theimage stabilization lens 108). The camera controller 205 displays on theimage display unit 206 the generated captured image as well as a number,a symbol, a mark, an icon, and the like indicating the imaging conditionsuperimposed on the captured image. A method in which the cameracontroller 205 acquires the magnification ratios and transmittances ofthe adapters 30 and 40 will be described later.

In the step S209, the camera controller 205 obtains operation dataindicating a user operation on the camera operation member 210 (referredto as camera operation data hereinafter), and acquires the first adapteroperation data and the second data from the adapter operation members312 and 412. The camera operation data is data indicating exposure(F-number, shutter speed, etc.) and zoom position setting by operating adial or electronic ring, instructions for AF/image stabilizationexecution/stop by operating a switch, and the like. The first and secondadapter operation data will be described later. Further, processing inwhich the camera controller 205 acquires the first and second adapteroperation data will be described later.

In the step S210, the camera controller 205 determines lens control databased on the lens state data acquired in the step S207, the cameraoperation data and the first and second adapter operation data acquiredin the step S209. More specifically, the camera controller 205 acquiresa phase difference from a phase difference sensor provided in the imagesensor 204 in response to turning on of a switch instructing theexecution of AF, and calculates a defocus amount of the imaging opticalsystem using the phase difference. Moreover, it determines a drivingamount of the focus lens 105 for obtaining the in-focus state from thecalculated defocus amount. The camera controller 205 determines thedriving amount of the magnification varying lens 106 based on dataindicating the operation amount of the dial or the electronic ring.Further, the camera controller 205 determines the driving amount of theiris 107 based on the exposure setting value set by operating the dialand the luminance level of the image signal generated using the outputfrom the image sensor 204. Further, the camera controller 205 determineswhether or not the image stabilization lens 108 can be driven inaccordance with turning on and off of a switch that instructs theexecution and stop of the image stabilization.

In this way, the camera controller 205 determines the lens control dataincluding the driving amounts of the focus lens 105, the magnificationvarying lens 106, and the iris 107 and whether or not the imagestabilization is available.

Next, in S211, the camera controller 205 transmits a lens controlcommand including lens control data to the lens controller 114 via thefirst camera communicator 207 (and the first lens communicator 115).

Next, in S212, the lens controller 114 passes the lens control dataincluded in the received lens control command to the focus, zoom andiris controllers 109, 110, and 111. The focus, zoom, and iriscontrollers 109, 110, and 111 drive the focus lens 105, the zoom lens106, and the iris 107 according to the lens control data. The lenscontroller 114 notifies the image stabilization controller 112 ofwhether or not the image stabilization included in the lens control datais available. When the image stabilization is permitted, the imagestabilization controller 112 shifts the image stabilization lens 108 soas to reduce the image shake according to the camera shake amountdetected by the shake detection unit 113.

As described above, in the initial communication (when the system isactivated) between the camera 20 and the interchangeable lens 10, thelens specific information, such as the name, specification, and lenscorrection data of the interchangeable lens 10, is communicated. Duringthe subsequent activation of the system, the data indicating the stateof the imaging optical system of the interchangeable lens 10 includingthe focal length and the focus position, the data indicating the contentof the operation performed on the camera 20 by the user, the above lenscontrol data, and the like are communicated at a predetermined timing.

Referring now to FIGS. 3A and 3B, a description will be given ofprocessing in which the first camera communicator 207 detects thecommunication voltage of the interchangeable lens 10 and communicationprocessing in the first communication.

FIG. 3A illustrates a configuration of the first communication channel100 for performing the first communication. In order to form the firstcommunication channel 100 connected from the camera 20 to theinterchangeable lens 10 via the adapters 30 and 40, the firstcommunication contacts 102, 303, 306, 403, 406, and 202 have thefollowing terminals.

The first communication contact 303 includes a first communication LCLKterminal 303 a, a first communication DCL terminal 303 b, a firstcommunication DLC terminal 303 c, and a TYPE terminal 303 d. The firstcommunication contact 306 includes a first communication LCLK terminal306 a, a first communication DCL terminal 306 b, a first communicationDLC terminal 306 c, and a TYPE terminal 306 d. The first communicationcontact 403 includes a first communication LCLK terminal 403 a, a firstcommunication DCL terminal 403 b, a first communication DLC terminal 403c, and a TYPE terminal 403 d. The first communication contact 406includes a first communication LCLK terminal 406 a, a firstcommunication DCL terminal 406 b, a first communication DLC terminal 406c, and a TYPE terminal 406 d.

First communication LCLK terminals 102 a, 303 a, 306 a, 403 a, 406 a,and 202 a are provided to form a line for a clock signal LCLK outputfrom the first camera communicator 207 (referred to as an LCLK linehereinafter). First communication DCL terminals 102 b, 303 b, 306 b, 403b, 406 b, and 202 b are also provided in order to form a line for thecamera data signal DCL output from the first camera communicator 207(hereinafter referred to as a DCL line). In addition, firstcommunication DLC terminals 102 c, 303 c, 306 c, 403 c, 406 c, and 202 care also provided to form a lens data signal DLC line (hereinafterreferred to as a DLC line) output from the first lens communicator 115.Each of the DLC line and the DCL line corresponds to a first datacommunication channel used during data communication. The LCLK linecorresponds to a first notification channel used for notification ofcommunication timing via the DCL line or the DLC line. The firstcommunication is not limited to clock synchronous communicationdescribed later, and may be performed by an asynchronous communication.

TYPE terminals 102 d, 303 d, 306 d, 403 d, 406 d, and 202 d are alsoprovided for forming an interchangeable lens type detection signal TYPEline (referred to as a TYPE line hereinafter) for detecting thecommunication voltage of the interchangeable lens 10. Four lines betweenthe first communication contacts 303, 306, 403, and 406 provided in theadapters 30 and 40 constitute a relay channel that forms part of thefirst communication channel 100.

As illustrated in FIG. 3A, the LCLK line and the DCL line are pulled upin the interchangeable lens 10. The LCLK line and the DLC line arepulled up in the camera 20.

The LCLK line, DCL line, DLC line, and TYPE line in the adapters 30 and40 are short-circuited between the first communication contacts 303 and306 and between the first communication contacts 403 and 406,respectively.

The TYPE line is pulled down by a predetermined resistance value foreach communication voltage in the interchangeable lens 10, and pulled upby a predetermined resistance value in the camera 20. The first cameracommunicator 207 detects the voltage value of the TYPE line, andspecifies the communication voltage of the interchangeable lens 10 basedon the voltage value determined from the resistance value in theinterchangeable lens 10 and the resistance value in the camera 20.

FIG. 3B illustrates a communication format example of the firstcommunication. This figure illustrates signal waveforms on the LCLKline, the DCL line, and the DLC line. The following description willrefer to the clock signal LCLK as an LCLK signal, the camera data signalDCL transmitted and received through the DCL line as a DCL signal, andthe lens data signal DLC transmitted and received through the DLC lineas a DLC signal.

The first camera communicator 207 outputs the LCLK signal to the LCLKline, and outputs eight-bit data B7 to B0 as the DCL signal to the DCLline in synchronization with the leading edge of the LCLK signal. Thefirst lens communicator 115 outputs eight-bit data B7 to B0 as a DLCsignal to the DLC line in synchronization with the leading edge of theLCLK signal.

The first camera communicator 207 receives eight-bit (B7 to B0) datafrom the DLC line in synchronization with the leading edge of the LCLKsignal. The first lens communicator 115 receives eight-bit (B7 to B0)data from the DCL line in synchronization with the leading edge of theLCLK signal. Thereby, the first camera communicator 207 and the firstlens communicator 115 can communicate data with each other.

When receiving the eight-bit data from the DCL line, the first lenscommunicator 115 puts the voltage level of the LCLK line into low forthe predetermined time Tbusy, and releases the low level when thepredetermined time Tbusy passes. In other words, it puts the voltagelevel into high. The predetermined time Tbusy is a time for processingthe data received by the lens controller 114, and during this time, thefirst camera communicator 207 does not transmit data to the first lenscommunicator 115. By repeating this communication processing, a datacommunication of a plurality of bytes is performed between the firstcamera communicator 207 and the first lens communicator 115 by the firstcommunication.

In the second communication, the one-way communication may be performedfrom the interchangeable lens 10 to the camera 20 by the same clocksynchronous communication as the first communication, or may beperformed by the asynchronous communication. The third communication maybe performed as the clock synchronous communication or the asynchronouscommunication as the bidirectional communication between the camera 20and the adapters 30 and 40 and between the interchangeable lens 10 andthe adapters 30 and 40, by a master-slave method or token passingmethod, etc.

FIG. 11A illustrates a communication format example of the asynchronouscommunication performed in the second communication on the secondcommunication channel 200. Herein, one frame is illustrated as theillustrative format of the data to be communicated, which includes tenbits or one-bit start bit, eight-bit data bits, one bit-stop bit. Thedata bits may be seven or sixteen bits, and may include a parity bit.The stop bits may have two bits.

FIG. 11B illustrates a timing synchronization method of the asynchronouscommunication in the second communication. The camera controller 205(and the second camera communicator 208) and the lens controller 114(and the second lens communicator 117) send and receive data insynchronization with the internal clock in accordance with apredetermined clock frequency or the clock rate. For example, theinternal clock is set to a clock rate 16 times as high as thecommunication rate between the camera controller 205 and the lenscontroller 114. The starting point of data sampling is determined bysampling the trailing edge of the start bit of the received data insynchronization with the internal clock, as shown as the synchronizationtiming in the figure. As illustrated as a data sampling timing in thefigure, the data is latched at a position of eight clocks starting fromthis synchronization timing. Thereby, the data can be captured at thecenter of each bit. By performing this data sampling for each bit, thedata communication is performed using only one second communication line(lens-camera transmission channel: DLC2).

The third communication channel 300 is a communication channel providedto enable the communication between the camera 20 and the adapters 30and 40. The third communication channel 300 is used to transmit acommand indicating an instruction to transfer to the power saving modefrom the camera controller 205 to the adapter controllers 311 and 411and the lens controller 114. Herein, the power saving mode is a mode inwhich the power consumption is lower than that in the normal operation.For example, the power saving mode is a mode that prohibits the datafrom being transmitted and received, and the movable optical element andthe optical elements 309 and 409 in the imaging optical system frombeing driven. Moreover, the third communication channel 300 is also usedto transmit a command indicating a communication counterpart in theone-to-one communication. It is also used to transmit information uniqueto the adapter controllers 30 and 40 to the camera controller 205. Theinformation unique to the adapter controllers 30 and 40 will bedescribed later.

Referring now to FIGS. 12 and 13, a description will be given of theasynchronous communication performed using the third communicationchannel 300. The third communication channel 300 includes two signallines, or a notification channel CS used to communicate thecommunication timing and a data communication channel DATA used totransmit and receive the data. Herein, the data communication channelDATA corresponds to a second data communication channel used during thedata communication. The notification channel CS corresponds to a secondnotification channel used for the notification of the timing of thecommunication via the data communication channel DATA.

FIG. 12 illustrates communication waveforms of the asynchronouscommunication performed in the third communication in the thirdcommunication channel 300. In particular, it illustrates theillustrative one-to-many communication in which data can be transmittedsimultaneously from an apparatus on the data transmission side to anapparatus on a plurality of data reception sides. More specifically, thecamera 20 transmits the data, and then the adapter 30 (or adapter 30)transmits the data. The communication performed by such a one-to-manycomponent will be referred to as the broadcast communicationhereinafter.

FIG. 12 illustrates one integrated signal output from the two adapters30 and 40 (adapter controllers 311 and 411).

When all of the camera controller 205, the adapter controllers 311 and411, and the lens controller 114 are configured to output High to thenotification channel CS, the signal level of the notification channel CSbecomes high. On the other hand, when at least one of the cameracontroller 205, the adapter controllers 311 and 411, and the lenscontroller 114 outputs Low to the notification channel CS, the signallevel of the notification channel CS becomes Low.

In the third communication, a communication speed is set in advance onboth the data transmission side and the data reception side, and thedata communication is performed at a communication bit rate based onthis setting. The communication bit rate indicates a data amounttransferable per second, and its unit is bps (bit per second).

When no data communication is performed, the signal level of the datacommunication channel DATA is maintained at the high level. Next, inorder to notify the data reception side of the start of datatransmission, the signal level of the data communication channel DATA isset to be Low for one bit period. This one-bit period will be called astart bit ST, and a data frame starts with the start bit ST. One-bytedata is transmitted in an eight-bit period from the second bit to theninth bit following the start bit ST.

The notification channel CS is connected to the camera controller 205,the adapter controllers 311 and 411, and the lens controller 114, andeach controller can detect the signal level (voltage level) of thenotification channel CS. Further, the notification channel CS ispull-up-connected to an unillustrated power source disposed in thecamera 20.

Each controller can set the signal level of the notification channel CS,and all the controllers 205, 311, 411, and 114 set the signal level ofthe notification channel CS to be high so that the signal level of thecommunication channel CS becomes high. In addition, when one of thecontrollers sets the signal level of the notification channel CS to low,the signal level of the communication channel CS becomes low.

In the third communication, the communication is performed using thecamera controller 205 (and the third camera communicator 209) as thecommunication master and the adapter controllers 311 and 411 and thelens controller 114 as the communication slaves.

The camera controller 205 that is the communication master notifies theadapters 30 and 40 and the interchangeable lens 10 that arecommunication slaves of the start of communication by outputting Low tothe notification channel CS. Next, the camera controller 205 transmitsthe data to the adapters 30 and 40 and the interchangeable lens 10 viathe data communication channel DATA. On the other hand, the adaptercontrollers 311 and 411 and the lens controller 114 output Low to thenotification channel CS in response to detecting the start bit STdescribed above via the data communication channel DATA. When theadapter controllers 311 and 411 and the lens controller 114 output Lowto the notification channel CS, the signal level of the notificationchannel CS remains Low because the camera controller 205 outputs Low.

The adapter controllers 311 and 411 and the lens controller 114 notifythe communication standby request by outputting Low to the notificationchannel CS. The communication standby request is for temporarilystopping the communication in the camera system, and the presence orabsence of the communication standby request is determined based on thesignal level of the notification channel CS.

The camera controller 205 outputs High to the notification channel CSafter transmitting all the data. After receiving the stop bit SPtransmitted from the data communication channel DATA, the adaptercontrollers 311 and 411 and the lens controller 114 execute an analysisof the received data and internal processing corresponding to thereceived data. Thereafter, after the preparation for executing the nextcommunication is completed, High is output to the notification channelCS.

The camera controller 205, the adapter controllers 311 and 411, and thelens controller 114 confirm that each controller is ready to perform thenext communication when the signal level of the notification channel CSreturns to High.

In FIG. 12, the data transmitted by the camera controller 205 includes atransmission requesting command for the adapter controllers 311 and 411,and the adapter controllers 311 and 411 provide a data transmissionfollowing a data transmission by the adapter controllers 311 and 411.More specifically, after the signal level of the notification channel CSbecomes High, the adapter controllers 311 and 411 output Low to thenotification channel CS. This notifies the lens controller 114 and thecamera controller 205 of the start of the communication. Next, theadapter controllers 311 and 411 transmit data to the lens controller 114and the camera controller 205 via the data communication channel DATA.

On the other hand, the lens controller 114 and the camera controller 205output Low to the notification channel CS in response to detecting theabove start bit ST via the data communication channel DATA. When thelens controller 114 and the camera controller 205 output Low to thenotification channel CS, the adapter controllers 311 and 411 output Lowto the notification channel CS, so the signal level of the notificationchannel CS remains Low.

The adapter controllers 311 and 411 output High to the notificationchannel CS after transmitting all the data. After receiving the stop bitSP transmitted from the data communication channel DATA, the lenscontroller 114 and the camera controller 205 execute an analysis of thereceived data and internal processing corresponding to the receiveddata. Then, after the preparation for executing the next communicationis completed, High is output to the notification channel CS.

When the camera controller 205, the adapter controllers 311 and 411, andthe lens controller 114 all output High to the notification channel CS,the signal level of the notification channel CS becomes High. The cameracontroller 205, the adapter controllers 311 and 411, and the lenscontroller 114 can confirm that each controller is ready to perform thenext communication when the signal level of the notification channel CSreturns to High.

FIG. 13 illustrates communication waveforms of the asynchronouscommunication performed in the third communication in the thirdcommunication channel 300. In particular, an example is illustrated inwhich communication is individually performed between the camera 20 andone component (one of the interchangeable lens 10 and the adapters 30and 40) selected as the communication counterpart by the camera 20.Hereinafter, the communication performed by such a one-to-one componentwill be referred to as a P2P communication.

Information indicating a communication slave that is a communicationcounterpart in the P2P communication is transmitted from the cameracontroller 205 by the broadcast communication. In the P2P communication,the data transmission side does not output Low to the notificationchannel CS, and transmits data to the data reception side whilemaintaining the notification channel CS to be High. In other words, thevoltage level of the notification channel CS during the datatransmission from the camera 20 to the interchangeable lens 10 and theadapter 30 is made different between the broadcast communication and theP2P communication.

When the broadcast communication is switched to P2P communication, thedata transmission first starts from the camera controller 205 which isthe communication master.

FIG. 13 illustrates an example in which a two-byte data transmission isperformed from the lens controller 114 to the camera controller 205after a one-byte data transmission is made from the camera controller205 to the lens controller 114.

After switching from the broadcast communication to the P2Pcommunication is completed in each component constituting the camerasystem, the camera controller 205 as the communication master transmitsdata to the lens controller 114 via the data communication channel DATA.When completing the data transmission, the camera controller 205notifies the communication standby request by setting the signal levelof the notification channel CS to a low output. The camera controller205 then returns the signal level of the notification channel CS to ahigh output after the preparation for receiving data is completed forthe data receiving side.

On the other hand, the lens controller 114 recognizes that the datatransmission from the camera controller 205 is completed due to thesignal level of the notification channel CS becoming Low, and executesan analysis of the received data and the internal processingcorresponding to the received data. In the example of FIGS. 5A and 5B,the data received from the camera controller 205 includes a datatransmission request from the lens controller 114 to the cameracontroller 205, and the lens controller 114 generates data to betransmitted to the camera controller 205.

Thereafter, when the signal level of the notification channel CS returnsto High, the lens controller 114 that has recognized the cancellation ofthe communication standby request transmits two-byte data to the cameracontroller 205.

When the data transmission ends, the lens controller 114 notifies thecommunication standby request by setting the signal level of thenotification channel CS to the low output. Then, the lens controller 114returns the signal level of the notification channel CS to the highoutput after the preparation for receiving the data is completed for thedata receiving side. The adapter microcomputer 302 that is not selectedas the communication counterpart of the P2P communication does notchange the output to the notification channel CS or does not participatein the data transmission/reception.

The lens controller 114 determines whether the P2P communicationcontinues or is switched to the broadcast communication depending on thedata transmission timing from the camera controller 205 after returningthe signal level of the notification channel CS to High.

The signal level of the notification channel CS while the cameracontroller 205 is transmitting data is made different between thebroadcast communication and the P2P communication. When the data fromthe camera controller 205 is received while the signal level of thenotification channel CS remains high (second voltage level), the lenscontroller 114 determines that the P2P communication continues. On theother hand, when the data from the camera controller 205 is receivedafter the signal level of the notification channel CS is changed to thelow level (first voltage level), the lens controller 114 determines thatthe P2P communication has been switched to the broadcast communication.

As described above, in the P2P communication, the data transmission sidechanges the signal level of the notification channel CS from the highoutput to the low output to notify the data reception side that the datatransmission by the data transmission side is completed. Therefore, inthe P2P communication, a plurality of data frames can be continuouslytransmitted until the data transmission side changes the signal level ofthe notification channel CS. Thereby, a high-speed communication can beperformed between the camera 20 and the accessory apparatus such as theinterchangeable lens 10, the adapter 30, and the microcomputer 302.Then, the data transmission side notifies the communication standbyrequest by maintaining the low signal output level of the notificationchannel CS until the data reception preparation is completed for thedata reception side in the next communication.

Referring now to a flowchart in FIG. 4, a description will be given ofprocessing in which the camera controller 205 acquires the magnificationratio of the adapter optical element (magnification variable lens) 309,the transmittance of the adapter optical element (ND filter) 409, andthe first and second adapter operation data.

S401 and S402 are the same as S201 and S202 in FIG. 2. The cameracontroller 205 that has proceeded from S402 to S403 transmits a commandthat requests the adapter controller 311 to transmit the first adapteroptical data, which is optical data of the adapter optical element 309,via the third camera communicator 209 (and the third adaptercommunicator 310).

In the step S404, the adapter controller 311 transmits the first adapteroptical data stored in the internal memory to the camera controller 205via the third adapter communicator 310 (and the third cameracommunicator 209). The first adapter optical data is data indicating themagnification ratio of the adapter optical element 309.

In the step S405, the camera controller 205 transmits a command thatrequests the adapter controller 411 to transmit the second adapteroptical data that is optical data of the adapter optical element 409 toit via the third camera communicator 209 (and the third adaptercommunicator 410).

In the step S406, the adapter controller 411 transmits the secondadapter optical data stored in the internal memory to the cameracontroller 205 via the third adapter communicator 410 (and the thirdcamera communicator 209). The second adapter optical data is dataindicating the transmittance of the adapter optical element 409.

Next, in the step S407, the camera controller 205 sends a command thatrequests the adapter controller 311 to transmit the first adapteroperation data, which is operation data of the adapter operation member312, to it via the third camera communicator 209 (and the third adaptercommunicator 310).

Next, in S408, the adapter controller 311 acquires an operational amountand an operation state from the adapter operation member 312. Then, dataindicating them is transmitted as first adapter operation data to thecamera controller 205 via the third adapter communicator 310 (and thethird camera communicator 209). When the adapter operation member 312 isan electronic ring, the first adapter operation data is data indicatingan operation amount per unit time of the electronic ring. When theadapter operation member 312 is a switch, the data indicates the ON/OFFstate of the switch.

In the step S409, the camera controller 205 sends a command thatrequests the adapter controller 411 to transmit the second adapteroperation data, which is operation data of the adapter operation member412, to it via the third camera communicator 209 (and the third adaptercommunicator 410).

Next, in S410, the adapter controller 411 acquires an operational amountand an operation state from the adapter operation member 412. Then, dataindicating them is transmitted as second adapter operation data to thecamera controller 205 via the third adapter communicator 310 (and thethird camera communicator 209). The second adapter operation data isdata similar to the first adapter operation data. By repeating theprocessing from S407 to S410, the camera controller 205 can periodicallyacquire the operation data of the adapter operation member 312 and theadapter operation member 412.

For example, when the aperture position adjusting function is assignedto the adapter operation member 312, the camera 20 instructs theinterchangeable lens 10 to change the aperture position via the firstcommunication channel 100 in accordance with the operation amount of theadapter operation member 412 acquired in S410. When the ON/OFF functionof the image stabilization function is assigned to the adapter operationmember 312, the camera 20 instructs the interchangeable lens 10 to turnon or off the image stabilization control via the first communicationchannel 100 in accordance with the operation state (ON or OFF) of theadapter operation member 412 acquired in S410. This is similarly appliedto the adapter operation member 412. The user can control the state ofthe imaging optical system of the interchangeable lens 10 through theoperations of the adapter operation members 312 and 412.

The above embodiment has described the magnification ratio andtransmittance of the adapter optical elements 309 and 409 as theillustrative first and second adapter optical data.

Information unique to the adapter 30 or information unique to theadapter 40 other than the first and second adapter optical data may becommunicated via the third communication channel 300. The informationunique to the adapter 30 may include, for example, at least one of aname and a specification of the adapter 30, and correction data of theadapter optical element 309. Similarly, the information unique to theadapter 40 may include, for example, at least one of the name andspecification of the adapter 40, and correction data of the adapteroptical element 409. For example, at least one of the name,specification, correction data of the adapter optical elements 309 and409 is transmitted to the camera 20 during the initial communicationbetween the camera 20 and the adapter 30 and between the camera 20 andthe adapter 40.

Further, when the state of the imaging optical system of theinterchangeable lens 10 or adapter optical element 309 or 409, etc.changes, and thereby the focal length information, the lighttransmittance information, etc. changes over time, the adapters 30 and40 may transmit these update data to the camera 20 in a normal statesuch as an ongoing imaging standby. Due to the above processing, thecamera controller 205 can acquire the magnification ratio and thetransmittance of the adapter optical elements 309 and 409 just afterstarting the power supply, and periodically acquire the operation amountand the operation state of the adapter operation members 312 and 412, assoon as the start of the power supply.

Referring now to FIGS. 5A and 5B, a description will be given of anoccupancy status of communication data in the first communicationchannel 100, the second communication channel 200, and the thirdcommunication channel 300. This description assumes that the lenscontrol command, the lens state data, and the adapter operation data allhave the same size.

FIG. 5A illustrates the occupancy state of the communication data in thecommunication channel in the camera system as a comparative examplehaving only one communication channel. The horizontal axis in the figureindicates time. Ta1, Ta2, Ta3, and Ta4 indicate transmission times ofthe lens control command, lens state data, first adapter operation data,and second adapter operation data, respectively. Ca1 and Ca2 indicatetransmission intervals between the lens control commands and between thelens state data, respectively.

The lens transmission requesting command is a command (data) for thecamera controller 205 to request the lens controller 114 to transmit thelens state data. The lens controller 114 transmits the lens state datato the camera controller 205 in response to receiving the lenstransmission requesting data. The first adapter transmission requestingdata and the second adapter transmission requesting command are data forthe camera controller 205 to request the adapter controllers 309 and 409to transmit the first and second adapter operation data, respectively.In response to receiving the first and second adapter transmissionrequesting data, the adapter controllers 311 and 411 transmit the firstand second adapter operation data to the camera controller 205,respectively.

In FIG. 5A, since the lens control command, the lens state data, and thefirst and second adapter operation data are sequentially communicated ina single communication channel, the transmission intervals Ca1 and Ca2become longer between the lens control data and between the lens statedata. The adapter controllers 311 and 411 need to correspond to the samecommunication speeds as those of the lens controller 114 and the cameracontroller 205.

On the other hand, FIG. 5B illustrates the occupancy state of thecommunication data in the camera system according to this embodimenthaving the first communication, the second communication, and the thirdcommunication channel 300. The horizontal axis in the figure indicatestime. Tb1, Tb2, Tb3, and Tb4 indicate transmission times of the lenscontrol command, the lens state data, the first adapter operation data,and the second adapter operation data, respectively. Cb1 and Cb2indicate transmission intervals between lens control commands andbetween lens state data, respectively.

As illustrated in FIG. 5B, the lens control command, the lens statedata, and the first and second adapter operation data are communicatedthrough communication channels different from each other. Thereby, thecamera controller 205 performs the first communication regardless ofwhether the camera controller 205 and the adapter controllers 30 and 40are performing the third communication. Further, the lens controlcommand, the lens state data, and the first and second adapter operationdata are communicated through communication channels different from eachother, so that the transmission interval Cb1 between the lens controlcommands is sufficiently shorter than Ca1 illustrated in FIG. 5A.Similarly, the transmission interval Cb2 between the lens state data isalso sufficiently shorter than Cb1. Thereby, the camera 20 can controlthe interchangeable lens 10 at a higher speed than the comparativeexample of FIG. 5A.

This embodiment limits devices connected to the first and secondcommunication channels 200 to the camera 20 and the interchangeable lens10. Thereby, compared with a case where another device (adapter) isconnected to the communication channel of the camera 20 and theinterchangeable lens 10 as in the comparative example, a signal can beprevented from degraded due to the reflection of signals to becommunicated. As a result, the communication speed can be made higherbetween the camera 20 and the interchangeable lens 10 in comparison withthe comparative example. Hence, if the communicated data sizes are thesame, Tb1 and Tb2 are shorter than Ta1 and Ta2. Furthermore, since thedevices connected to the second communication channel 200 are limited tothe camera 20 and the interchangeable lens 10, it is unnecessary totransmit the lens transmission requesting command from the camera 20 tothe interchangeable lens 10 and the transmission interval between thelens state date can be made shorter.

In this embodiment, the transmission times Tb3 and Tb4 of the first andsecond adapter operation data are longer than Tb3 and Tb4. Thiseliminates the need for the adapters 30 and 40 to support a high-speedcommunication by setting the communication rate of the thirdcommunication slower regardless of the communication rates of the firstand second communications.

Further, in this embodiment, the lens control command, the lens statedata, the first adapter operation data, and the second adapter operationdata can be communicated at an arbitrary communication timing withoutbeing obstructed by the channel occupancy due to the other datacommunication. For example, a communication is available not only duringthe initial communication performed when the interchangeable lens,adapters 30 and 40, and the like are attached to the camera 20, but alsoduring the ongoing imaging standby or ongoing imaging operation in thecamera 20.

As described above, this embodiment performs a communication of avariety of commands and data performed among the camera 20, theinterchangeable lens 10, and the adapters 30 and 40 at propercommunication timings without being obstructed by another communication.In comparison with a case where there is only one communication channel,various commands and data can be more stably communicated at shortintervals, and the stability of the interchangeable lens control, theoperability of the adapter, etc. can be improved.

Further, since only the camera 20 and the interchangeable lens 10 areconnected to the first and second communication channels 200, the firstand second communications can be expedited and enhanced in function, andthe controllability of the interchangeable lens can be further improved.In addition, when the camera 20 switches the communication voltageaccording to the communication voltage of the interchangeable lens 10, aplurality of interchangeable lenses having different communicationvoltages can be connected to the camera 20. Further, by performing thethird communication between the camera 20 and the adapters 30 and 40separately from the first and second communication, it is unnecessary touse an adapter that matches the high communication speed of the camera20 and the interchangeable lens 10. As described above, for example, thecamera 20 can be realized which can be mounted with both an oldinterchangeable lens corresponding to the first communication having ahigh communication voltage and having no contacts with the secondcommunication and the third communication and a new interchangeable lenscorresponding to the first communication, the second communication, andthe third communication having low communication voltages for the lowpower consumption. In this case, the cost of the electric circuit can bereduced for the new interchangeable lens since the new interchangeablelens can set a low communication voltage for the first communication,and can communicate at the same voltage as the low communicationvoltages of the second communication and the third communication.

This embodiment has described the adapters 30 and 40 communicating thefirst and second adapter operation data to the camera 20 through thethird communication. However, the interchangeable lens 10 maycommunicate data relating to the interchangeable lens 10 (such as lensoperation data) to the camera 20 via the third lens communicator 117,the third adapter communicator 310, and the third camera communicator209.

In addition, the interchangeable lens that performs the communicationwith a communication voltage different from the communication voltagesof the adapters 30 and 40 may not have the third lens communicator 117or the third communication contact 104. This configuration can preventthe third lens communicator 117 and the third adapter communicators 310and 410 from being connected with the communication voltages differentfrom each other.

Second Embodiment

Referring now to FIG. 6, a description will be given of a secondembodiment of the present invention. In this embodiment, those elements,which are corresponding elements in the first embodiment, will bedesignated by the same reference numerals and a description thereof willbe omitted.

In this embodiment, the camera individually transfers theinterchangeable lens and the adapter between a normal operation state(first state: referred to as a normal state hereinafter) that provides acommunication, and a low power consumption state (second state: referredto as a sleep state hereinafter) that does not provide a communicationand is lower in power consumption than that in the normal state. Whenthe interchangeable lens is in the sleep state, this embodiment uses thefirst communication channel 100 as a channel for transmitting a lensactivation signal for activating the interchangeable lens. When theadapter is in the sleep state, this embodiment uses the thirdcommunication channel 300 as a channel for transmitting an adapteractivation signal that starts the adapter. The lens activation signaland the adapter activation signal are transmitted to the interchangeablelens and the adapter by a transmission method different from the firstcommunication and the third communication performed in the normal state.

In FIG. 6, when an interchangeable lens 10′ is in the sleep state, thecamera controller 2201 in a camera 20′ sends the lens activation signalto a lens controller 2101 via a camera sleep state signal controller2202 and the first communication channel 100. The lens controller 2101in the interchangeable lens 10′ receives the lens activation signal fromthe camera controller 2201 via the first communication channel 100 andthe lens sleep state signal controller 2102 when the interchangeablelens 10′ is in the sleep state. Furthermore, when the adapters 30′ and40′ are in the sleep state, the camera controller 2201 sends the adapteractivation signal to adapter controllers 2301 and 2401 in adapters 30′and 40′ via the camera sleep state signal controller 2202 and the thirdcommunication channel 300.

A flowchart in FIG. 7 illustrates processing in which the camera 20′transfers the interchangeable lens 10′ from the normal operation state(referred to as a normal state hereinafter) to the sleep state, andreturns the interchangeable lens 10′ to the normal state. The normalstate of the interchangeable lens 10′ means a state in which theinterchangeable lens 10′ can perform the first, second, and thirdcommunications, and the camera 20′ can control driving of the movableoptical element in the imaging optical system of the interchangeablelens 10′. The sleep state of the interchangeable lens 10′ indicates astate in which the interchangeable lens 10′ stops the first, second, andthird communications and consumes the power lower than the normal state.

In the step S702, the camera controller 2201 that has started processingin S701 acquires the camera operation data and the first and secondadapter operation data described in the first embodiment. Then, the flowproceeds to S703.

In S703, the camera controller 2201 determines whether the time duringwhich there is no change in the camera operation data or the first andsecond adapter operation data has exceeded a predetermined time. Inother words, it is determined whether or not the non-operation timeduring which the operation members 207, 312, and 412 of the camera 20′or the adapters 30′ and 40′ are not operated by the user exceeds thepredetermined time. If the non-operation time exceeds the predeterminedtime, the camera controller 2201 proceeds to S704, and if not (if thereis an operation), the camera controller 2201 repeats the processing ofS703. The predetermined time is time enough to determine that the useris not performing an operation for imaging, such as several seconds.

In S704, the camera controller 2201 transmits a command requesting thelens controller 2101 to transfer to the sleep state via the first cameracommunicator 207 (and the first lens communicator 115). Then, the flowproceeds to S705.

In S705, the lens controller 2101 transfers the interchangeable lens 10′to the sleep state in response to the request to transfer to the sleepstate received through the first lens communicator 115. Only the lenssleep state signal controller 2102 operates in the interchangeable lens10′ in the sleep state.

In the step S706, the camera controller 2201 acquires the cameraoperation data and first and second adapter operation data again. Then,the flow proceeds to S707.

In S707, the camera controller 2201 determines whether or not the cameraoperation data or the first and second adapter operation data acquiredin S702 and S706 has changed. In other words, it is determined whetheror not the operation members 207, 312, and 412 of the camera 20′ or theadapters 30′ and 40′ are operated by the user. The camera controller2201 proceeds to step S708 when determining that the operation has beenperformed, and otherwise (if there is no operation) repeats thedetermination in the step S707.

In S708, the camera controller 2201 outputs a lens activation signal tothe first communication channel 100 via the camera sleep state signalcontroller 2202. Processing for outputting the lens activation signal tothe first communication channel 100 will be described later.

Next, in S709, the lens sleep state signal controller 2102 to which thelens activation signal is input activates the lens controller 2101 andtransfers the interchangeable lens 10′ to the normal state. Then, thisflow ends.

By this processing, the camera controller 2201 can transfer only theinterchangeable lens 10′ from the normal state to the sleep state, andcan transfer from the sleep state to the normal state.

Referring now to FIG. 8, a description will be given of processing foroutputting the lens activation signal to the first communication channel100. FIG. 8 illustrates signal waveforms on the LCLK line, the DCL line,and the DLC line when the camera sleep state signal controller 2202outputs the lens activation signal.

When the lens activation signal is input from the camera controller 2201in the step S708 in FIG. 7, the camera sleep state signal controller2202 outputs the LCLK signal to the LCLK line from time Tc10, andoutputs a specific data bit string (B7 to B0). The LCLK signal and aspecific data bit string signal are transmitted as a lens activationsignal to the lens sleep state signal controller 2102.

The lens sleep state signal controller 2102 activates the lenscontroller 2101 in response to detecting a change in at least one of theLCLK line and the DCL line in the sleep state. Thereby, theinterchangeable lens 10′ transfers to the normal state. Thereafter, thefirst lens communicator 115 outputs Low to the LCLK line for apredetermined time Tbusy, and cancels the Low output at time Tc11 whenthe predetermined time Tbusy passes. Thereafter, the first communicationillustrated in FIG. 3B can be performed between the camera controller2201 and the lens controller 2101.

This processing can transfer only the interchangeable lens 10′ from thesleep state to the normal state using the first communication channel100.

Referring now to FIG. 9, a description will be given of processing fortransferring the interchangeable lens 10′ from the sleep state to thenormal state in accordance with the operation of the lens operationmember 118. FIG. 9 illustrates signal waveforms on the LCLK line, theDCL line, and the DLC line when the interchangeable lens 10′ transfersfrom the sleep state to the normal state in accordance with theoperation of the lens operation member 118.

When the lens sleep state signal controller 2102 detects the operationof the lens operation member 118, the lens sleep state signal controller2102 outputs Low as the lens activation request signal to the DLC linefrom time Tlc0 illustrated in FIG. 9. When the camera sleep state signalcontroller 2202 detects Low on the DLC line, the first cameracommunicator 207 outputs the LCLK signal to the LCLK line from time Tlc1and outputs a specific data bit string (B7 to B0) to the DCL line. TheLCLK signal and a specific data bit string signal are transmitted as alens activation signal to the lens sleep state signal controller 2102.

The lens sleep state signal controller 2102 activates the lenscontroller 2101 in response to detecting a change in at least one of theLCLK line and the DCL line in the sleep state of the interchangeablelens 10′. Thereby, the interchangeable lens 10′ transfers to the normalstate. Thereafter, the first lens communicator 115 cancels the lowoutput on the DLC line at time Tlc2. Thereafter, the first lenscommunicator 115 outputs Low to the LCLK line for the predetermined timeTbusy, and cancels the Low output when the predetermined time Tbusyelapses. Thereafter, the first communication illustrated in FIG. 3B canbe performed between the camera controller 2201 and the lens controller2101.

This processing can transfer only the interchangeable lens 10′ to thenormal state using the first communication channel 100 in response tothe operation of the lens operation member 118 of the interchangeablelens 10′ in the sleep state.

Referring now to a flowchart in FIG. 10, a description will be given ofprocessing in which the camera 20′ transfers the adapters 30′ and 40′from the normal state to the sleep state and again transfers theadapters 30′ and 40′ to the normal state. The normal state of theadapters 30′ and 40′ is a state in which the adapters 30′ and 40′ canperform the third communication and the camera 20′ can control drivingof the movable optical element of the imaging optical system of theinterchangeable lens 10′. The sleep state of the adapters 30′ and 40′indicates a state where the adapters 30′ and 40′ stop the thirdcommunication and consume the power lower than that in the normal state.

In the step S1002, the camera controller 2201 that has started theprocess in S1001 acquires the camera operation data and the lensoperation data described in the first embodiment. Then, the flowproceeds to S1003.

In S1003, the camera controller 2201 determines whether or not the timeduring which the camera operation data or the lens operation data hasnot changed exceeds a predetermined time. In other words, it isdetermined whether or not the non-operation time during which theoperation members 207 and 118 of the camera 20′ or the interchangeablelens 10′ are not operated by the user exceeds the predetermined time. Ifthe non-operation time exceeds the predetermined time, the cameracontroller 2201 proceeds to S1004, and if not (if there is anoperation), the camera controller 2201 repeats the processing of S1003.The predetermined time is time enough to determine that the user is notperforming an operation for imaging, such as several seconds.

In S1004, the camera controller 2201 transmits a command requesting theadapter controllers 2301 and 2401 to transfer to the sleep state via thethird camera communicator 209 (and the third adapter communicators 310and 410). Then, the flow proceeds to S1005.

In S1005, the adapter controllers 2301 and 2401 cause the adapters 30′and 40′ to transfer to the sleep state, respectively. Only the adaptersleep state signal controllers 2302 and 2402 operate in the adapters 30‘and 40’ in the sleep state.

In the step S1006, the camera controller 2201 acquires the cameraoperation data and lens operation data again. Then, the flow proceeds toS1007.

In S1007, the camera controller 2201 determines whether there is achange in the camera operation data or the lens operation data acquiredin S1002 and S1006. In other words, it is determined whether or not theoperation members 207 and 118 of the camera 20′ or the interchangeablelens' are operated by the user. If the camera controller 2201 determinesthat the operation has been performed, the flow proceeds to step S1008;otherwise (if there is no operation), the determination in the stepS1007 is repeated.

In S1008, the camera controller 2201 outputs an adapter activationsignal to the third communication channel 300 via the camera sleep statesignal controller 2202. The processing of outputting the adapteractivation signal to the third communication channel 300 is the same asthe processing of outputting the lens activation signal to the firstcommunication channel 100 described above.

Next, in 51009, the adapter sleep state signal controllers 2302 and 2402activate the adapter controllers 2301 and 2401, respectively, and causethe adapters 30′ and 40′ to transfer to the normal state. Then, thisprocessing ends.

This processing allows the camera controller 2201 to shift only theadapters 30 ‘and 40’ from the normal state to the sleep state, and fromthe sleep state to the normal state.

Further, the processing of transferring the adapters 30′ and 40′ fromthe sleep state to the normal state according to the operation of theadapter operation members 312 and 412 is similar to the method fortransferring the interchangeable lens 10′ to the normal state accordingto the operation of the lens operation member 118 described above. Inother words, in response to the operation of the adapter operationmembers 312 and 412 of the adapters 30′ and 40′ in the sleep state, theadapter activation request signal is transmitted to the camera 20′ usingthe third communication channel 300. Then, the adapter activation signalis transmitted from the camera 20′ to the adapters 30′ and 40′ using thethird communication channel 300. Thereby, only the adapters 30′ and 40′can be transferred from the sleep state to the normal state.

According to this embodiment, the camera 20′ can transfer theinterchangeable lens 10′ and the adapters 30′ and 40′ to the normalstate and the sleep state without depending on their states. Hence, aproper power control can be performed according to the use situationsand types of the interchangeable lens and the adapter. For example, whenthe camera 20′ is driven by a battery and the camera 20′ detects thatthe battery power has lowered, only the adapter can be put into a sleepstate, thereby making the camera imaging time as long as possible.

The embodiment described above has described two adapters arrangedbetween the interchangeable lens 10 and the camera 20, but the number ofadapters is not limited to this embodiment. The present invention isapplicable to an interchangeable lens, a camera, and an adapterconstituting a camera system in which at least one adapter can bedisposed between the interchangeable lens 10 and the camera 20.

Other Embodiments

Embodiment(s) of the present invention can also be realized by acomputer of a system or apparatus that reads out and executes computerexecutable instructions (e.g., one or more programs) recorded on astorage medium (which may also be referred to more fully as a‘non-transitory computer-readable storage medium’) to perform thefunctions of one or more of the above-described embodiment(s) and/orthat includes one or more circuits (e.g., application specificintegrated circuit (ASIC)) for performing the functions of one or moreof the above-described embodiment(s), and by a method performed by thecomputer of the system or apparatus by, for example, reading out andexecuting the computer executable instructions from the storage mediumto perform the functions of one or more of the above-describedembodiment(s) and/or controlling the one or more circuits to perform thefunctions of one or more of the above-described embodiment(s). Thecomputer may comprise one or more processors (e.g., central processingunit (CPU), micro processing unit (MPU)) and may include a network ofseparate computers or separate processors to read out and execute thecomputer executable instructions. The computer executable instructionsmay be provided to the computer, for example, from a network or thestorage medium. The storage medium may include, for example, one or moreof a hard disk, a random-access memory (RAM), a read only memory (ROM),a storage of distributed computing systems, an optical disk (such as acompact disc (CD), digital versatile disc (DVD), or Blu-ray Disc (BD)™),a flash memory device, a memory card, and the like.

While the present invention has been described with reference toexemplary embodiments, it is to be understood that the invention is notlimited to the disclosed exemplary embodiments. The scope of thefollowing claims is to be accorded the broadest interpretation so as toencompass all such modifications and equivalent structures andfunctions.

The present invention can realize a camera, an interchangeable lensapparatus, and an adapter apparatus, each of which can expedite acommunication between the camera and the interchangeable lens apparatusand smooth a communication between the camera and the adapter apparatus.

The embodiments described above are merely representative examples, andvarious modifications and changes may be made to the embodiments whenthe present invention is implemented.

What is claimed is:
 1. A camera to which an interchangeable lensapparatus is capable to be connected via at least one adapter apparatus,the camera comprising: a lens-camera communication controller configuredto communicate with the interchangeable lens apparatus by using acamera-lens communication channel; and an adapter-camera communicationcontroller configured to communicate with the adapter apparatus by usinga camera-adapter communication channel provided separately from thecamera-lens communication channel.
 2. The camera according to claim 1,wherein the camera-lens communication channel includes a first datacommunication line used during a data communication, a second datacommunication line used during a data communication and a firstnotification line used for a notification of a timing of a communicationbetween the camera and the interchangeable lens apparatus, and whereinthe camera-adapter communication channel includes a second datacommunication line used during the data communication and a secondnotification line used for a notification of a timing of a communicationbetween the camera and the adapter apparatus.
 3. The camera according toclaim 1, wherein the lens-camera communication controller performs thecommunication regardless of whether the adapter-camera communicationcontroller is communicating or not.
 4. The camera according to claim 2,wherein the communication via the lens-camera communication channel andthe communication via the adapter-camera communication channel aredifferent from each other in at least one of communication method,communication timing, communication rate and communication voltage. 5.The camera according to claim 1, wherein the lens-camera communicationcontroller transmits a lens control command for controlling an operationof the interchangeable lens apparatus, to the interchangeable lensapparatus.
 6. The camera according to claim 1, wherein theadapter-camera communication controller receives unique information ofthe adapter apparatus from the adapter apparatus.
 7. The cameraaccording to claim 6, wherein the unique information includes opticaldata of the adapter apparatus.
 8. The camera according to claim 1,wherein the adapter-camera communication controller receives operationdata indicating a user operation for the adapter apparatus, from theadapter apparatus.
 9. The camera according to claim 2, wherein thelens-camera communication controller detects a communication voltageused by the interchangeable lens apparatus in the camera-lenscommunication channel, and sets the communication voltage to be used forthe communication with the interchangeable lens apparatus in thecamera-lens communication channel according to a result of thedetection.
 10. The camera according to claim 2, wherein theadapter-camera communication controller receives data relating to theinterchangeable lens apparatus from the interchangeable lens apparatusvia the camera-adapter communication channel.
 11. The camera accordingto claim 2, wherein each of the lens-camera communication controller andthe adapter-camera communication controller individually performs acommunication to transfer the interchangeable lens apparatus and theadapter apparatus from a first state in which the communication isperformed to a second state in which no communication is performed. 12.The camera according to claim 11, wherein the lens-camera communicationcontroller transmits a lens activation signal for transferring theinterchangeable lens apparatus from the second state to the first state,or a lens activation requesting signal for requesting the second stateof the interchangeable lens apparatus output from the interchangeablelens apparatus to the first state, via the camera-lens communicationchannel, by a communication method different from the communication inthe first state.
 13. The camera according to claim 11, wherein theadapter-camera communication controller transmits an adapter activationsignal for transferring the adapter apparatus from the second state tothe first state, or an adapter activation requesting signal forrequesting the second state of the adapter apparatus output from theadapter apparatus to the first state, via the camera-adaptercommunication channel, by a communication method different from thecommunication in the first state.
 14. The camera according to claim 2,wherein the adapter-camera communication controller is configured toswitch between a first communication method used to communicate amongthe interchangeable lens apparatus, the at least one adapter apparatus,and the camera, and a second communication method used to individuallycommunicate with either the interchangeable lens apparatus or the atleast one adapter apparatus and different from the first communicationmethod in voltage level of the second notification line whiletransmitting data to a communication counterpart.
 15. The cameraaccording to claim 14, wherein the adapter-camera communicationcontroller sets the voltage level of the second notification line duringa data transmission in the first communication method to a first level,and sets the voltage level of the second notification line during a datatransmission in the second communication method to a second level higherthan the first level.
 16. The camera according to claim 14, wherein theadapter-camera communication controller transmits, via the second datacommunication line in the first communication method, communicationcounterpart designation data indicating a communication counterpart ofthe camera in the second communication method.
 17. A camera systemcomprising: a camera to which an interchangeable lens apparatus iscapable to be connected via an adapter apparatus, the camera-comprising:a lens-camera communication controller configured to communicate withthe interchangeable lens apparatus by using a camera-lens communicationchannel; and an adapter-camera communication controller configured tocommunicate with the adapter apparatus by using a camera-adaptercommunication channel provided separately from the camera-lenscommunication channel, the interchangeable lens apparatus connected tothe camera; and the adapter apparatus connected to the camera and theinterchangeable lens apparatus.
 18. The camera system according to claim17, wherein the camera-lens communication channel includes a first datacommunication line used during a data communication, a second datacommunication line used during a data communication and a firstnotification line used for a notification of a timing of a communicationbetween the camera and the interchangeable lens apparatus, and whereinthe camera-adapter communication channel includes a second datacommunication line used during the data communication and a secondnotification line used for a notification of a timing of a communicationbetween the camera and the adapter apparatus.
 19. An adapter apparatusto which the camera and interchangeable lens apparatus are capable to beconnected, the adapter apparatus comprising: a relay channel for formingpart of a camera-lens communication channel used for a communicationbetween the camera and the interchangeable lens apparatus; and anadapter-camera communication controller configured to communicate withthe camera by using a camera-adapter communication channel providedseparately from the relay channel.
 20. The adapter apparatus accordingto claim 19, wherein the camera-lens communication channel includes afirst data communication line used during a data communication, a seconddata communication line used during a data communication and a firstnotification channel used for a notification of a timing of thecommunication between the camera and the interchangeable lens apparatus,and wherein the camera-adapter communication channel includes a seconddata communication line used during a data communication and a secondnotification line used for a notification of a timing of a communicationbetween the camera and the adapter apparatus.
 21. An interchangeablelens apparatus connected to an adapter apparatus and a camera via theadapter apparatus, the interchangeable lens apparatus comprising: afirst lens-camera communication controller configured to communicatewith the camera by using a camera-lens communication channel; and asecond lens-camera communication controller provided separately from thecamera-lens communication channel and configured to communicate with thecamera by using a communication channel including a camera-adaptercommunication channel connected to the camera and the adapter.
 22. Theinterchangeable lens apparatus according to claim 21, wherein thecamera-lens communication channel includes a first data communicationchannel used during a data communication, a second data communicationline used during a data communication and a first notification channelused for a notification of a timing of communication via the first datacommunication channel, and wherein the camera-adapter communicationchannel includes a second data communication channel used during a datacommunication and a second notification channel used for a notificationof a timing of a communication via the second data communicationchannel.